Mistletoe lectin-I augments antiproliferative effects of the PPARgamma agonist rosiglitazone on human malignant melanoma cells

Phytohemagglutinin from Phaseolus vulgaris enhances the lung cancer cell chemotherapy sensitivity by changing cell membrane permeability

Chemotherapy is still a prevalent strategy for clinical lung cancer treatment. However, the inevitable emerged drug resistance has become a great hurdle to therapeutic effect. Studies have demonstrated that the primary cause of drug resistance is a decrease in the chemotherapeutic medicine concentration. Several lectins have been confirmed to be effective as chemotherapy adjuvants, enhancing the anti-tumor effects of chemotherapy drugs. Here, we combined phytohemagglutinin (PHA), which has been reported possess anti-tumor effects, with chemotherapy drugs Cisplatin (DDP) and Adriamycin (ADM) on lung cancer cells to detect the sensitivities of PHA as a chemotherapy adjuvant. Our results demonstrated that the PHA significantly enhanced the sensitivity of lung cancer cells to DDP and ADM, and Western blot showed that PHA combined with DDP or ADM enhance cytotoxic effects by inhibiting autophagy and promoting apoptosis. More importantly, we found PHA enhanced the chemotherapeutic drugs cytotoxicity by changing the cell membrane to increase the intracellular chemotherapeutic drugs concentration. Besides, the combination of PHA and ADM increased the ADM concentration in the multidrug-resistant strain A549-R cells and achieved the drug sensitization effect. Our results suggest that PHA combined with chemotherapy can be applied in the treatment of lung cancer cells and lung cancer multidrug-resistant strains, and provide a novel strategy for clinical tumor chemotherapy and a new idea to solve the problem of drug resistance in clinical lung cancer.

Effect of mistletoe extract on tumor response in neoadjuvant chemoradiotherapy for rectal cancer: a cohort study

Background

Mistletoe extract, used as a complementary chemotherapeutic agent for cancer patients, has anticancer effects against various malignancies. The aim of the present study was to evaluate the effect of mistletoe extract (Abnoba Viscum Q®) on tumor responses to neoadjuvant chemoradiotherapy (NCRT) for locally advanced rectal cancer.

Methods

This study included patients with rectal cancer who underwent NCRT between January 2018 and July 2020. In the mistletoe group (MG), the patients were administered Abnoba Viscum Q® subcutaneously during chemoradiotherapy—maintained just before surgery. Patient demographics, clinical outcomes, histopathological outcomes, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) assay results were compared between the MG and non-mistletoe group (NMG). Two rectal cancer cell lines (SNU-503 and SNU-503R80Gy) were treated with Abnoba Viscum Q® to assess its mechanistic effects in vivo.

Results

Overall, the study included 52 patients (MG: n = 15; NMG: n = 37). Baseline demographics between the two groups were similar, except carbohydrate antigen 19-9 levels and tumor location from the anal verge. There was no difference in the clinical stage between the two groups. A better tumor response in the MG, relative to the NMG, was observed with respect to tumor regression grade (TRG), T stage, and overall tumor–node–metastasis stage. Tumor response was significantly better in the MG than in the NMG in terms of pathologic complete response rate (53.3% vs. 21.6%, P = 0.044), good TRG response (66.7% vs. 32.4%, P = 0.024), T downstaging (86.7% vs. 43.2%, P = 0.004), and overall downstaging (86.7% vs. 56.8%, P = 0.040). The toxicities during NCRT were minimal in both groups. More apoptotic cells were noted in MG samples than in the NMG samples on TUNEL staining. Cleaved caspase-3 level following treatment with Abnoba Viscum Q® was higher in SNU-503R80Gy cells than in SNU-503 cells.

Conclusion

Patients treated with chemoradiation combined with mistletoe extract showed better outcomes than patients not treated with mistletoe extract in terms of tumor responses. This diversity in treatment may improve the efficacy of NCRT, leading to better oncologic outcomes. Prospective and randomized studies with long-term follow-up are warranted to confirm and extend these results.

New insights into molecular mechanisms of rosiglitazone in monotherapy or combination therapy against cancers

Rosiglitazone (ROSI), a member of thiazolidinediones (TZDs) which act as high-affinity agonists of the nuclear receptor peroxisome-proliferator-activated receptor-γ (PPARγ), is clinically used as an antidiabetic drug which could attenuate the insulin resistance associated with obesity, hypertension, and impaired glucose tolerance in humans. However, recent studies reported that ROSI had significant anticancer effects on various human malignant tumor cells. Mounting evidence indicated that ROSI could exert anticancer effects through PPARγ-dependent or PPARγ-independent ways. In this review, we summarized the PPARγ-dependent antitumor activities of ROSI, which included apoptosis induction, inhibition of cell proliferation and cancer metastasis, reversion of multidrug resistance, reduction of immune suppression, autophagy induction, and antiangiogenesis; and the PPARγ-independent antitumor activities of ROSI, which included inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, inhibition of prostaglandin E2 (PGE₂), increasing MAPK phosphatase 1 (MKP-1) expression and regulation of other apoptosis-related cell factors. In addition, we discussed the anti-cancer application of ROSI by monotherapy or combination therapy with present chemotherapeutic drugs in vitro and in vivo. Moreover, we reviewed the phase I cancer clinical trials related to ROSI combined with chemotherapeutics and phase II trials about the anti-cancer effects of ROSI monotherapy and the radiotherapy sensitivity of ROSI.

Proliferation, Apoptosis and Invasion effects of mistletoe alkali on human osteosarcoma U2OS in vitro

OBJECTIVE

To evaluate the effects of mistletoe alkali on human Osteosarcoma cells (U2OS) in vitro.

SUMMARY OF BACKGROUND DATA

Osteosarcoma is the most common primary malignant tumor of bone tumor, although there are a lot of therapies such as surgery, radiotherapy and chemotherapy, its prognosis is still very poor. There is increasing interest in the protective biological function of natural antioxidants contained in Chinese medicinal herbs, which are candidates for the prevention of tumors. Mistletoe alkali is one of the compounds extracted from Viscum coloratum (Komar.) Nakai, one kind of mistletoe, whose extracts contribute to the improvement of the prognosis of patients with malignancies.

METHODS

The effect of mistletoe alkali on the growth of U2OS cells was compared with 5-FU, using a Cell Counting Kit-8 (CCK-8). The influence of mistletoe alkali on U2OS's proliferation and apoptosis were tested by TUNEL staining and immunocytochemical (ICC) staining of caspase 3 and proliferating cell nuclear antigen (PCNA). Additionally, the invasion ability of U2OS cells was detected using a Boyden chamber trans-well migration assay.

RESULTS

CCK-8 assays gave an IC50 of 7μg/ml for mistletoe alkali. Compared to 5-FU, mistletoe alkali inhibited U2OS proliferation and induced apoptosis more effectively. The invasion ability of U2OS was also weaker in mistletoe alkali than in 5-FU.

CONCLUSIONS

Mistletoe alkali significantly inhibited growth and invasion abilities of U2OS cells and induced their apoptosis in vitro. Mistletoe alkali may be a more effective drug for Human Osteosarcoma than the standard chemotherapeutic drug 5-FU.

Emerging roles of mistletoes in malignancy management

Mistletoes are a group of obligate plant semi-parasites in the order Santalales. These clumps of plants growing on a wide range of host plants have been traditionally regarded as medicinal repositories. However, current scientific discoveries have validated their health potentials like never before. Their extracts containing alkaloids, viscotoxins, lectins, and polysaccharides have been evidenced to possess a myriad biological potentials including cancer inhibition. Mistletoes have emerged as promising alternative therapy against colon, oral, lung, and pancreas cancers. The plant extracts bolster immunity, delay tumour initiation and progression, kill malignant tumours, stabilize DNA, alleviate side effects of chemotherapeutics, improve the lifespan, and coping ability of cancer patients and survivors. A range of proprietary formulations viz. Iscador, Eurixor, Helixor, Lektinol, Isorel, Iscucin, Abnoba-viscum and recombinant lectin ML-1 are already being commercialized. This review presents an informative account on the recent developments in mistletoe-mediated cancer management. The underlying mechanisms, possibilities and limitations in cancer therapeutic development are outlined for kindling both researcher and public interest.

PPARγ-dependent pathway in the growth-inhibitory effects of K562 cells by carotenoids in combination with rosiglitazone

BACKGROUND

Carotenoids have been found to play roles in the prevention and therapy of some cancers which PPARγ was also discovered to be involved in. The present studies were directed to determine the inhibitory effects of carotenoids in combination with rosiglitazone, a synthetic PPARγ agonist, on K562 cell proliferation and elucidate the contribution of PPARγ-dependent pathway to cell proliferation suppression.

METHODS

The effects of carotenoid and rosiglitazone combination on K562 cell proliferation were evaluated by trypan blue dye exclusion assay and MTT assay. When PPARγ has been inhibited by GW9662 and siRNA, cycle-related regulator expression in K562 cells treated with carotenoid and rosiglitazone combination was analyzed by Western blotting.

RESULTS

Rosiglitazone inhibited K562 cell proliferation and augmented the inhibitory effects of carotenoids on the cell proliferation greatly. Specific PPARγ inhibition attenuated the cell growth suppression induced by carotenoid and rosiglitazone combination. GW9662 pre-treatment attenuated the enhanced up-regulation of PPARγ expression caused by the combination treatment. Moreover, GW9662 and PPARγ siRNA also significantly attenuated the up-regulation of p21 and down-regulation of cyclin D1 caused by carotenoids and rosiglitazone.

CONCLUSIONS

PPARγ signaling pathway, via stimulating p21 and inhibiting cyclin D1, may play an important role in the anti-proliferative effects of carotenoid and rosiglitazone combination on K562 cells.

GENERAL SIGNIFICANCE

Carotenoids in combination with rosiglitazone are hopeful to provide attractive dietary or supplementation-based and pharmaceutical strategies to treat cancer diseases.